This invention relates generally to the salvage of dynamoelectric machine components and in particular to a method for stripping windings from a stator for a dynamoelectric machine.
Dynamoelectric machines, such as an electric motor or the like, are provided with a stator having a pair of opposite and generally parallel end faces intersected by a bore extending axially therebetween through the stator. A plurality of winding receiving slots are also provided in the stator about the bore thereof and intersecting with both the bore and the opposite end face. A plurality of windings generally respectively constituted by a preselected number of turns of copper or aluminum wire or the like are wound or otherwise inserted by means well-known in the art into the stator winding slots. In this manner, opposite sides of the winding turns are disposed within the stator slots, and opposite ends of the winding turns span across a selected number of stator slots adjacent the intersections thereof with the opposite end faces of the stator exteriorly thereof. These opposite ends of the winding turns are respectively formed into generally annular groupings extending from the opposite end faces radially outwardly of the stator bore and are known to the art as end turns. Of course, if desired, the particular wire of the windings may have an insulating coating thereon, and slot liners and wedges of suitable insulating material may be provided between the windings and the stator. Further, in some instances, the stators may be assembled by various means and methods generally well-known to the art as bonding. For a detailed discussion of one such bonded stator and method of assembly thereof reference may be had to U.S. Pat. No. 3,490,143 and U.S. Pat. No. Re. 26,788.
In the past, wound stators, such as described above, which were found to be defective for one reason or another either at the time of manufacture or after usage, were stripped of their windings. In this manner, salvaged stators which were in condition for reuse were rewound, and those which could not be used were sold for scrap. Of course, the stripped windings could not be salvaged and were sold for scrap. In some cases, the entire wound stator may have been sold for scrap, but due to the formidable increases in stator core material, it is now more economically prudent to salvage stators for reuse if possible.
In order to salvage stators, it is first necessary to sever one of the pair of opposite generally annular groupings of end turns of the stator windings therefrom, and various apparatus and methods have been employed in the past to sever one of the end turns from the stator windings. For a detailed description of one apparatus and method for severing end turns from stator windings reference may be had to U.S. Pat. application Ser. No. 541,740 filed Jan. 17, 1975. Further, various other apparatus and methods have been employed in the past to strip the windings from the stator after one of the end turns of the windings had been severed therefrom.
In some of the past apparatus and methods for stripping a winding from a stator, the stator was clamped by suitable clamping means in a desired position atop a table or work bench or the like with the remaining end turns of the stator windings facing upwardly. Tongs were then engaged with a part of the remaining end turns, and the tongs were then driven or pulled upwardly by a hoist or the like. The upward movement of the tongs pulled the remaining end turns and windings therewith to effect the stripping of the windings from the stator. One of the disadvantageous or undesirable features of such past apparatus and method was that too much time was consumed and too many operations were involved in mounting or clamping the stator onto a work table in preparation for the winding stripping operation. Further, another disadvantageous or undesirable feature of such past apparatus and methods was that the tongs would not be operable to completely strip all of the windings from the stator in one pulling operation since the windings poles are separate; therefore, it might be necessary to strip each of the winding poles in separate pulling operations from the stator.
In another of the past apparatus and methods for stripping the windings from a stator, the stator was first mounted to a fixture with the remaining end turns of the windings facing upwardly. A tool was then disposed on the upper end face of the stator having pins predeterminately disposed therein and adapted to be driven by a ram wedge generally radially outwardly to a displaced position interposed between the stator end face and each of the end turns of each of the winding poles. The stator and tool was then inverted on the fixture, and the tool was driven downwardly carrying the end turns of the stator windings on the displaced pins of the tool thereby to strip the windings from the stator. One of the disadvantageous or undesirable features of such past apparatus and method was that too much time was consumed and too many operations were involved with respect to tool placement and the inverting of the stator subsequent to the actuation of the tool for stripping the windings. Another disadvantageous or undesirable feature of such past apparatus and methods was that it may have been necessary to perform the stripping operation twice if the stator was provided with starting windings shifted in phase relation in the stator with respect to the running windings thereof.
In yet another of the past apparatus and method for stripping windings from a wound armature for a dynamoelectric machine, a mandrel was provided on a drill press or the like, and the remaining end turns of the windings were slipped upwardly onto or about a free or lower end of the mandrel by an operator. The free end of the mandrel was tapered so as to, in effect, spread or displace the winding end turns as they were manually moved upwardly onto the tapered free end of the mandrel. Of course, when the engagement between the remaining end turns and the mandrel become great enough, the operator released the armature, and it was thereby suspended from the mandrel free end. The mandrel with the armature suspended therefrom was then lowered into a fixture, and a plurality of cams on the fixture were pivoted thereon to rotatably move fingers or prongs on the cam to position interposed between the upper end face of the armature and the remaining end turns. Of course, since there was no predetermined position of the armature in which the cam fingers engaged the remaining end turns, it was necessary to adjustably raise and lower the mandrel in order to effect the interposition of the cam fingers between the stator end face and the remaining end turns. Thereafter, the mandrel was lowered further driving the armature relative to the windings supported on the cam fingers toward a portion displaced from the windings thereby to strip the windings from the armature. One of the disadvantageous or undesirable features of this past apparatus and method was that it lacked a predetermined or mounting position of the armature in which the cam fingers could be positively engaged with the winding end turns. Another disadvantageous or undesirable feature of the past apparatus and method was that the mounting position of the armature to the mandrel was variable for each armature since it depended upon the particular shaping of the end turns. And still another disadvantageous or undesirable feature of this past apparatus and method was that the mandrel had to be adjustably raised and lowered so as to locate the cam fingers in the interstices between the remaining end turns and the stator end face thereby to consume too much time and effect too many separate operations.